Clean up onvif and autotracking (#24559)

* simplify onvif and autotracking code

Removes about 230 lines from the ONVIF controller and autotracker without changing how PTZ moves are calculated. `OnvifController` no longer keeps its own `camera_configs` copy of the camera config, the cached `GetStatus`, `GetServiceCapabilities`, and `AbsoluteMove` request objects are gone in favor of plain dicts at the call site, and `PtzAutoTrackerThread` is merged into `PtzAutoTracker`. Repeated blocks in the autotracker (waiting for the motor to stop, disabling autotracking on a failed setup step) are now single helpers.

* use camera config for autotracking enabled state

Camera processes read autotracking state from a shared `autotracker_enabled` value that the dispatcher and autotracker had to keep in sync with the config by hand. Camera processes now subscribe to the `autotracking` and `onvif` config updates and read `onvif.autotracking.enabled` directly, so the shared value and the autotracker's mirroring method are gone. `_disable` now publishes its change so the camera process hears about it. Also removes `tracking_active`, which was set and cleared but never read.

* compute max target box from live zoom factor

* fix autotracking debug overlay max target box lookup

* make max target box a function of zoom factor

frigate/motion/improved_motion.py

@@ -19,6 +19,7 @@ class ImprovedMotionDetector(MotionDetector):
         config: RuntimeMotionConfig,
         fps: int,
         ptz_metrics: PTZMetrics | None = None,
+        autotracking_enabled: bool = False,
         name: str = "improved",
         blur_radius: int = 1,
         interpolation: int = cv2.INTER_NEAREST,
@@ -45,6 +46,7 @@ class ImprovedMotionDetector(MotionDetector):
         self.contrast_values[:, 1:2] = 255
         self.contrast_values_index = 0
         self.ptz_metrics = ptz_metrics
+        self.autotracking_enabled = autotracking_enabled
         self.last_stop_time: float | None = None
 
     def is_calibrating(self) -> bool:
@@ -59,8 +61,7 @@ class ImprovedMotionDetector(MotionDetector):
         # if ptz motor is moving from autotracking, quickly return
         # a single box that is 80% of the frame
         if self.ptz_metrics is not None and (
-            self.ptz_metrics.autotracker_enabled.value
-            and not self.ptz_metrics.motor_stopped.is_set()
+            self.autotracking_enabled and not self.ptz_metrics.motor_stopped.is_set()
         ):
             return [
                 (
@@ -162,7 +163,7 @@ class ImprovedMotionDetector(MotionDetector):
         # if so, reassign the average to the current frame so we begin with a new baseline
         if self.ptz_metrics is not None and (
             # ensure we only do this for cameras with autotracking enabled
-            self.ptz_metrics.autotracker_enabled.value
+            self.autotracking_enabled
             and self.ptz_metrics.motor_stopped.is_set()
             and (
                 self.last_stop_time is None